Certain types of motor racing (for example Formula 1 Grand Prix) traditionally takes place on tracks which include, or consist solely of, existing roadways, and it is therefore not feasible to have a track fence as a permanent installation, but the track fence must necessarily be capable of being erected and removed quickly and easily. It is also desirable that the interference with the existing road construction should be minimal.
Traditionally fences have been made with chain wire mesh forming a debris fence portion surmounting a concrete barrier, but chain mesh is not always strong enough to protect spectators on the outer side of the fence against such debris as runaway wheels which may be travelling at very high speed. Chain mesh is a material formed from wire, generally about 2.5 mm in thickness, the wire being interlaced and having portions which are bent from the plane of the fence so that there is a high degree of resilience. While resilience is desirable in one respect, that is that the deflection of the chain mesh enables the kinetic energy to be absorbed over a length of the fence, the resilience is undesirable in that the chain mesh is essentially supported by bar-like stiffeners, and if the mesh has been deflected the bar-like stiffeners can be subjected to direct impact forces which can be destructive of the fence. Furthermore, chain mesh interferes with spectator viewing.
One object of the invention therefore is to provide improvements whereby the debris portion of the fence is much stiffer, and in an embodiment of the invention use is made of weldmesh panel assemblies upstanding from the upper surfaces of concrete barriers, each panel assembly comprising a panel of weldmesh sheet supported at its ends by upstanding bar-like stiffeners. Weldmesh sheet is a sheet of material having wires extending in one direction overlying wires extending at right angles thereto and welded at each intersection. The wires are straight and are usually much thicker and stronger than the wires of chain mesh, and thereby the weldmesh panels will provide additional protection for the barlike stiffeners which are used to support them.
Race tracks which are used require closed circuits and therefore the fence must be not only capable of withstanding the very great forces imposed upon it by a motor vehicle crash, but must also be positionable either in a straight line, or in a curve the concave side of which faces the race track, or in a curve the convex side of which faces the race track, and a further object of the invention is to provide improvements whereby the advantages of weldmesh panels can be achieved and fence modules can be arranged either in line, or can hinge with respect to one another so as to be either convexly or concavely.